Malicious RTF — malware analysis report

Static analysis result for SHA-256 a218a173aed2b12f…

MALICIOUS

RTF

780.5 KB Created: 2019-07-25 13:36:00 First seen: 2019-11-20
MD5: 1a3e565a788a17036de31f8806d38ad0 SHA-1: 2fe699ea85184c0d153f765d5d6d8818b6f436bd SHA-256: a218a173aed2b12f228ab2fd0be0d208e06fb82546c8bba641bf5b0a3a7c2e12
362 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains an embedded OLE object that exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This vulnerability is known to be used to execute arbitrary code, likely to download and run a secondary payload. The ClamAV detection and heuristic firings strongly indicate a malicious dropper.

Heuristics 9

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • Equation Editor Ole10Native payload — CVE-2017-11882 likely critical CVE likely CVE_2017_11882_EQUATION_OLE10NATIVE
    RTF decodes to an activated Microsoft Equation 3.0 OLE storage whose payload is a high-entropy Ole10Native stream rather than normal Equation Native/MTEF data. This is a weaponized Equation Editor RCE delivery shape consistent with CVE-2017-11882/CVE-2018-0802.
  • Ole10Native stream in RTF OLE object high CVE related RTF_OLE10NATIVE_STREAM
    RTF contains an embedded OLE object with an Ole10Native stream. This is a strong payload-container signal and is related to Word/OLE exploit delivery, but it is not specific enough on its own to assign a CVE.
  • ClamAV: Rtf.Dropper.Agent-7082442-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-7082442-0
  • Suspicious extracted artifact critical EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.microsoft.com/office/word/2003/wordml In RTF body
    • https://bit.ly/2YlitJBIn RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000a3ba0.bin rtf-objdata-decoded RTF \objdata at offset 0xA3BA0 3622 bytes
SHA-256: 9659654649664cb912bca322472f213c014348888150c9395266cc64752763f3
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered URL(s): https://bit.ly/2YlitJB Static shellcode analysis found candidate code region(s). Indicators: SC_STR_LOADLIBRARY, SC_STR_URLDOWNLOAD, SC_PEB_ACCESS Static shellcode analysis recovered API/import strings: LoadLibraryA, GetProcAddress, URLDownloadToFileA, ExitProcess

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